1. Field of the Invention
The present invention relates to a method and system for processing X-ray images in an X-ray equipment.
2. Description of the Related Art
In conventional X-ray equipment, X-rays are radiated from an X-ray source as an X-ray tube onto a subject to be examined. The X-rays passed through the subject are converted into light by an image intensifier (I.I.), and the light is incident on an optical system. An X-ray image of the subject is formed by this light. The formed X-ray image is converted into a TV signal by a TV camera and is displayed on a TV monitor. When a predetermined portion of the subject is displayed on the TV monitor, an X-ray image is formed on an X-ray film by further radiating X-rays on the subject.
When the X-rays are passed through the subject, scattered X-rays are superposed on passed X-rays. These scattered X-rays degrade the quality of the X-ray image formed on the X-ray film. In the conventional X-ray equipment, therefore, in order to prevent incidence of scattered X-rays onto an image intensifier, a grid is arranged between a subject and the image intensifier. This grid has a mesh structure and hence can attenuate scattered X-rays which are obliquely radiated onto the image intensifier.
Recently, a CCD (Charge Coupled Device) is used as a TV camera of X-ray equipment. In X-ray photography using a CCD camera, however, the shadow of a grid is formed on an X-ray image. More specifically, if the resolution of the camera is lower than the maximum spatial frequency of a subject to be examined, a phenomenon called aliasing occurs. If a grid having cyclic fine meshes is arranged, a shadow such as moire fringes is formed on an image. Therefore, X-ray diagnostic information is degraded.
Under the circumstances, demands have arisen for an X-ray equipment which can eliminate a grid image formed on an X-ray image.